Suppression of enhanced physiological tremor via stochastic noise: initial observations.

Enhanced physiological tremor is a disabling condition that arises because of unstable interactions between central tremor generators and the biomechanics of the spinal stretch reflex. Previous work has shown that peripheral input may push the tremor-related spinal and cortical systems closer to anti-phase firing, potentially leading to a reduction in tremor through phase cancellation. The aim of the present study was to investigate whether peripherally applied mechanical stochastic noise can attenuate enhanced physiological tremor and improve motor performance.

Enhanced corticomuscular coherence by external stochastic noise.

Noise can have beneficial effects as shown by the stochastic resonance (SR) phenomenon which is characterized by performance improvement when an optimal noise is added. Modern attempts to improve human performance utilize this phenomenon. The purpose of the present study was to investigate whether performance improvement by addition of optimum noise (ON) is related to increased cortical motor spectral power (SP) and increased corticomuscular coherence.

Broad-band Gaussian noise is most effective in improving motor performance and is most pleasant.

Modern attempts to improve human performance focus on stochastic resonance (SR). SR is a phenomenon in non-linear systems characterized by a response increase of the system induced by a particular level of input noise. Recently, we reported that an optimum level of 0-15 Hz Gaussian noise applied to the human index finger improved static isometric force compensation.

A battery-driven, low-field NMR unit for thermally and hyperpolarized samples.

Object: The design of a multinuclear low-field NMR unit with variable field strength <6 mT providing accurate spin manipulations and sufficient sensitivity for direct detection of samples in thermal equilibrium to aid parahydrogen-based hyperpolarization experiments.

Materials And Methods: An optimized, resistive magnet connected to a battery or wall-power driven current source was constructed to provide a magnetic field <6 mT. A digital device connected to a saddle-shaped transmit- and solenoid receive-coil enabled MR signal excitation and detection with up to 10(6) samples/s, controlled by a flexible pulse-programming software.

The strength of the corticospinal coherence depends on the predictability of modulated isometric forces.

Isometric compensation of predictably frequency-modulated low forces is associated with corticomuscular coherence (CMC) in beta and low gamma range. It remains unclear how the CMC is influenced by unpredictably modulated forces, which create a mismatch between expected and actual sensory feedback. We recorded electroencephalography from the contralateral hand motor area, electromyography (EMG), and the motor performance of 16 subjects during a visuomotor task in which they had to isometrically compensate target forces at 8% of the maximum voluntary contraction with their right index finger.